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RE: [PATCH v2 net-next 3/4] secure_seq: use SipHash in place of MD5

From David Laight <David.Laight@ACULAB.COM>
Newsgroups linux.kernel
Subject RE: [PATCH v2 net-next 3/4] secure_seq: use SipHash in place of MD5
Date 2017-01-09 14:30 +0100
Message-ID <sXIbo-4KA-13@gated-at.bofh.it> (permalink)
References <sX0tH-1DJ-7@gated-at.bofh.it> <sX0tH-1DJ-9@gated-at.bofh.it> <sX6St-5J1-15@gated-at.bofh.it> <sX7lw-69Q-3@gated-at.bofh.it>
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From: Eric Biggers
> Sent: 07 January 2017 22:09
..
> Out of curiosity, is this actually a solvable problem, e.g. by making the code
> using the XMM registers responsible for saving and restoring the ones clobbered,
> or by optimizing kernel_fpu_begin()/kernel_fpu_end()?  Or does it in fact remain
> impractical for such instructions to be used for applications like this one?

I think it should be possible to fast-save a couple of FP registers
by telling the IPI save code where to save them from (to load
into a different cpu).
But there might be issues with other parts of the FP state.
This might be ok provided the kernel doesn't actually use FP instructions.

(I thought about this when adding AVX support to NetBSD.)

	David

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[PATCH v2 net-next 0/4] Introduce The SipHash PRF "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-01-07 15:50 +0100
  [PATCH v2 net-next 3/4] secure_seq: use SipHash in place of MD5 "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-01-07 15:50 +0100
    Re: [PATCH v2 net-next 3/4] secure_seq: use SipHash in place of MD5 David Miller <davem@davemloft.net> - 2017-01-07 22:40 +0100
      Re: [PATCH v2 net-next 3/4] secure_seq: use SipHash in place of MD5 Eric Biggers <ebiggers3@gmail.com> - 2017-01-07 23:10 +0100
        Re: [PATCH v2 net-next 3/4] secure_seq: use SipHash in place of MD5 David Miller <davem@davemloft.net> - 2017-01-08 02:50 +0100
        RE: [PATCH v2 net-next 3/4] secure_seq: use SipHash in place of MD5 David Laight <David.Laight@ACULAB.COM> - 2017-01-09 14:30 +0100
      Re: [PATCH v2 net-next 3/4] secure_seq: use SipHash in place of MD5 "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-01-08 13:30 +0100
  [PATCH v2 net-next 2/4] siphash: implement HalfSipHash1-3 for hash tables "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-01-07 15:50 +0100
  [PATCH v2 net-next 1/4] siphash: add cryptographically secure PRF "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-01-07 15:50 +0100
  Re: [PATCH v2 net-next 0/4] Introduce The SipHash PRF Eric Biggers <ebiggers3@gmail.com> - 2017-01-07 21:00 +0100
    Re: [PATCH v2 net-next 0/4] Introduce The SipHash PRF "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-01-08 13:50 +0100

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